The proposed research will investigate a new animal model of the effects of abused drugs upon perceptual function. The model focuses upon the auditory perception of biologically relevant, species-specific communication signals in primates and will provide for experimental studies on perceptual processes within the broader context of the social communication systems of the savanna baboon, Papio cynocephalus. The proposed research will 1) extend the analysis of the effects of drugs of abuse on perceptual processes to the perception of species-specific communication signals in baboons, and 2) examine the effects of major drugs of abuse such as stimulants and anxiolytics on the perception of communication signals associated with differing motivational and social contexts (e.g., affiliative, aggressive, submissive). The use of well-established psychophysical procedures will provide for precise, quantitative assessments of drug effects on perceptual function, and digitally generated exemplars of actual baboon calls will be employed to provide for precise control of relevant acoustic features. One set of experiments will compare the similarities of the previously- demonstrated effects of drugs of abuse on perception of speech sounds with the effects of drugs of abuse on the perception of species-specific vocalizations. A second set of experiments will examine the relationship between a drug's perceptual effects and the type of social communication signal being discriminated. A third set of experiments will examine the relationship between a drug's perceptual effects and the social rank of the sender and receiver of the signal. This research will provide fundamental data on the effects of drugs of abuse on perceptual function in nonhuman primates, and on the perception of communication signals of motivational and/or social significance. This research will advance our understanding of factors which contribute to the abuse liability of widely abused drugs, and will yield information directly relevant to the clinical implications of the perceptual effects associated with the use and abuse of drugs.